Method of cutting the teeth of spur gear-wheels.



A. DENKER.

METHOD 0F CUTTING THE TEETH OP SPUR GEAR WHEELS.

APPLICATION FILED EEB. 24, 1913.

A. DENKER. y METHOD OF CUTTING THE TEETH 0F SPUR GEAR WHEELS.

APPLICATION FILED FEB. 24, 1913.

Patented Nov.- 3, 1914.

2 SHEETS-SHEET 2.

UNITED STATES PATENT OFFICE.

AUGUST DENKER, OF TERNITZ-ON-THE-SDBAHN, AUSTRIA-HUNGARY, ASSIGNOR TO DIETEL-GESELLSCHAFT G. M. B. 'I-I., OF PRAGUE, AUSTRIA-HUNGARY.

METHOD OF CUTTING THE-TEETH 0F SPUR GEAR-WHEELS.

Specification of Letters Patent.

Patented Nov. 3.1914.

Continuation in part of application Serial No.` 559,676, fried May- 6, 1910'. This application filed February 24, 1913. Serial N o'. 750,462.

To all 'tv/wm t may conce-rn Be it known that I, AUGUST DENKER, a subject of the German Emperor, residing at Ternitz-on-the-Sdbahn, Austriaungary, have invented certain new and useful Improvements in Methods of Cuttlnghthef'.l1`1eeth t e o ow- .of each complete tooth space in a continuous operation before indexing for the cutting of the next tooth space, thusreducing largely sources of error aswell as effecting' a considera'ble saving in ,the timeV of operation. The method furthermore, is not limited by the diameter of the wheel blank to be cut. The nature of my invention will be best understood when described in connection with the accompanying drawings, in which-- Figures 1, 2 and 3 are diagramma-tic views illustrating the manner of cutting a tooth space, Fig. l showing the cutting tool in its initial position relativel to the wheel blank, Fig. 2, similarly the too in its' final osition after having completed the cutting o a complete tooth space, and `ig; 3 .variousintermediate positions which thecntting tool successively assumes relatively to the 'wheel blank. Fig. et is a side elevation of a` machine which maybe employed in cutting the teeth inthe novel manner herein claimed,

.only those parts of said machine being shown which are necessary for understanding' the inventin. Fig. 5 is a partial horizontal section of the machine with the wheel blank removed. `Fig. 6 is a view (p artly in `section) 'of the transmission I'nechamsm, ex-

tended for purposes of explanation, in one plane (not projected).

Similar characters of reference designate corresponding parts throughout the several views.

In carrying out my improved method of cutting involute teeth of spur gear wheels, by means of a reciprocating cutting` tool, I employ preferably a machine having y the general' arrangement of a vertical slotting' machine and in which the workl table4 or support for the wheel blank to .be cut is .arranged according to my invention to have av cross feed as well as av rotation on its vertical aXis, The forward edge ofthecuttin'g tool c in its initial position with respectfto thewheel blank s, upon beginningto cut a tooth space, is made 'to' lie in the tangent t0 therroot circle of theteeth, 1, and the blank translated y,in the directionof this gent toward said cutting tool (in the dieci -tion of the straight arrow, Fig. 1) whle'i'it is simultaneously therewith lrotated away from said too-l about its own Ivertical axis (in the direction of the curved,v arrow, Eig.

The combined motion of the ,wheel blank is equivalent to that produced by the rolling motion of a toothed wheel, having the saine pitch circle as the teeth of spur gear to be c ut, alongV a rack. Afterthe tool has cut a complete tooth space, various intermediate positions ofsaid tool relatively to said wheel'blank beingl shown in Fig'. 3, it reaches the position relatively to theA said wheel blankshown in Fi 2. The blankis then brought back in sui able nlanner to its and the cross-feed mec anism fsuit,ably disengaged from the rotating mechanism so that the latter may be independentl' ated to effect` the indexing. lAfter" this, the cross-feed 4and rotary feed mechanism are again connected (automatically) and the continueus operation of cutting a tooth space is repeated.

I n'Figs. Ll--inclusivel have illustratedmechanism suitablafor effecting these va.- rious operatic-ns. A horizontal Work table o'r support a for the wheel blank s' is mo'nnfed on the bed ofthe machine and isfcapb `of, being fed `along land also across theI bed,

and of being rotatedY on it's'own' ve'tical axis. The -table may ,be fedy along the bed by tin-ning shaft aan but thisy feed has no' essential relation'to the subject matter ofthe prsent invention, and Inay' be of any well known construction.

b is a shaft mounted on one' side ofthe initial position relatively to the cutting tol,

machine framing, end troni which the crossieed and therotation of the worlrtahle are derived.

d is pewl, actuated at each stroke of the tool rem hy means ot e connecting rod from the dri"ing shaft of the machine to ing a ratchet Wheel a?, Whereh is rotated intermittently at the end oi stroke oi" the tool.

Z) through hevel gears e to a The worktaole receives its cross-reed through a not 't 'formed on it engaging the cross-ieee` screiv g The rotation of the sheit f is els-o transmitted through a toothed Wheel i to toothed Wheel z' which is loose on -a shaft ,7c supported in the framing of the machine.

y The wheel i carries one hall3 Z of a clutch, the otherhalf Z2 of which is slidahly lreved onthe shaft 7s, which is connected through gearing 5v having ,a variable speed ratio1 to a Worin g' on shaft m. .The 'farces of the ciiitoh are so constructed that its halves Will be brought into engagement Wi o each other onlywhen they ere in a cef-sin position,

Lu This engagement is preferably elected maticelly, for instance hy ineens ci e spring n. Rotation of the werkte-.hie is eft'ecte through vthe Worin Q and Werne wheel fr o the seid Workt'ahle.

'llierelocity ratios of the gearing hetree` the shaft f and the cross-feed screw g ,of that hetvveen the clutch a ond the Worm shaftm, may be varied. in the usuel nia-.ener by changing a. pair of toothed wheels.

in order to out involute teeth, the cross-4 feed rotary feed of the Worltahle roest have e relation to the tool such as to import to the Wheel blank vto he cut, a motion equivalent to the rolling motion e toothed Wheel having the seme pitch circle along;Vn rack., For this purpose the velocity ratios or the gearing producing the cross-ieedend rotary 'feed of the tehle must he such that the rstio of the speed oi revolution oi" the cross- .feed screw g to the speed of revolution o" the shaft f will he equal to the ratio of th .pitch of the Wheel to he cut to the pitch o the driving Worin wheel connected to Worldahle. Further, the ratio oi the speed of revolution of the shaft 7c to speed oit revolution of ythe Worm g must he equal to the ratio ott the number ot teeth of the Wheeltohecut to the number of teeth of the .driving worm Wheel. i Also,` the speed of revolntion of the Tvvheel 7i moet here e ratio to. the speed otrevolution of the wheel i which is inverse to that of the pitch ofthe creseieedscrew gto the pitch of the worin g so es to compensate for the ditlerence hetweentheselast tivo pitches. (Consequently, the product oh'teined hy miiltiplyiha the veiaiiojeio feet screw g and shaft f retio oi the gearinfT between Worm g will he trie velocitv7 ratio of the cross-feed of the tahle to the peri jherel velocity of the worm Wheel.

New since the product oi' the moltiplication is the ratio ot the diameter of the pitch circle oit the Wheel 'to he cut 'to the diameter of the pitch circle of the driving worin wheel, the consequence is that the speed oi the cross-feed of the wheel blank to he out is equal to the speed of revolution at the pitch circle, that is to say, the motion o'l` the Wheel hlenlr is the same as the rolling motion of a. toothed Wheel havine a pitch circle of eouel diameter along7 a rack. "'f' for eX- emple, the Worm Wheel on the work table has 140 teeth with a circle or" circular pitch of 5ft millimeters, that is a pitch circle diameter of PIG() millimeters, and if it is de f' sired to cut e wheel with 100 teeth and fr circaler pitch of 12e millimeters, that is a pitch circle diameter of 1200 millimeters, then the ratio .of the speed of revolution ot the ci'oss-ieed screw y; vto the speed of revolation or the shaft f inust he as l2 to 5, and the ratio of the speed of revolution of the sheit'k to the speed of revolution of the worin g einst he as l0() to 140. The product of multiplication of these two ratios is 12 ioo iaoo 5 le@ pZ0() and the ratio of 1200 to 700 will hothe ratio of the speed oil the cross-feed of the ivorktahle to the peripheral speed of the Worm Wheel et the pitch circle.

loo

Now since the ratio of the pitch circle I diameter of the Wheel to he cut, to the pitch circle diameter' of the Worin wheel, is likewise as 1200 to 700, it is clear that the ratio of the peripheral speed of the wheel to he out to the `peripheral speed of the worin `wheel, will likewise he as to 700; that is to say, the peripheral speed at the pitch circle of the Wheel to he out, is equal to the amount of cross-feed of the worlrtahle.

The operation of the improved machine is as iolloivszmllhe wheel blank' s to he cut having heen iixed on the Worlitahle a and hrought into the position shown in Fig. l

relatively to the cutting tool such that the forward edge of said tool lios in the tangent to the root circle of the teeth to he cut, the machine is started. During the up end down v.moveizfient of the cutting tool, the wheel locity retio oi the geering hetweeo the crossl heck into its initial position by means of hand cranks placed on the end of the shaft m or the cross-feed screw g,lafter which the parts of the clutch are disconnected, and the shaft m is rotated independently of the spindle g, until after the .shaft c has made a complete revolution, whereupon the clutch is automatically connected v again through the yaction of the spring n.

Since the velocity ratio of the shaft 7c to the worm g corresponds to the'ratio ofthe number of teeth of the wheel to be .cut to the number of teeth of the driving worm wheel, therefore, after the shaft k has made a complete revolution, the wheel blank s will have been rotated through an angle correspondingto the pitch of the wheel to be cut, that is in the example under consideration, through an angle of 3 degrees 36 minutes, which corresponds to a circular pitch of 121:. v

If it is desired to cut toothed wheels having a different pitch, or a diiferent number of teeth, it will be'necessary to change merely one pair of toothed wheels of the gearing between the shaft f and the screw' g, or one pair of toothed wheels of the gearing between the shaft le and the worm shaft m. When both the pitch andv the number of teeth are to be different, one pair of toothed wheels will have to be changed in both gearings.L

The improved machine is very much simpler to construct andmanipulate than" the existing shaping or slotting machines for cutting gear teeth;` and the present improvements are easily applicable to every. existing shaping or slotting machine.

I claimz. v

l. The herein described method of cut ting teeth of spur gear wheels, which con.- sists in directing the edge of the cuttingtool to the wheel blank to be cut tangentially to the root circle of the teeth, and imparting simultaneously v to said blank a translation toward said tool in the direction of the said tangent .and a rotation'k about its own axis.

2. The herein described method of cutting teeth of'spur gear wheels, which consists in directing the edge ofthe cutting i parting ysimultaneously to said blank a translation toward said toolin the direction of the said tangent and a rotation about its-own axis to cut a tooth space, and suitably indexing upon the cuttmg of a complete tooth space.

3. The herein described method of cutting teeth of spur gear wheels, which con-l its own laxis to cut a tooth space, returning.

said blank to its initial position with respect to the cutting tool, and then indexing to bring said cutting tool into 'position to cut the next tooth space.

4. The vherein described method of cutting involute teeth of spur gear wheels, which consists in directing the edge of the cutting tool to the wheel blank to be cut tangentially to the root circle of the teeth, and imparting simultaneously to said blank a translation toward said tool in the direction of the said tangent and a rotation about its own axis such that the resultant motion of the wheel blank shall be equivalent to the rolling motion of a toothed wheel, of the same pitch circle, along a rack.

5. The herein described method of cut-` next tooth space.

In testimony whereof, I have signed my name to this specification in the presence of two subscribing witnesses. Y

. AUGUST DENKER.

Witnesses:

ADA MARIA BERGER, AUGUST FUGGER. 

